Proximity sensors have long been used to detect the presence of an object that is positioned near the proximity sensor. For example, many modern restrooms have proximity sensors installed in sinks. The presence of a person's hands under the sink faucet is sensed by a proximity sensor which then sends a signal to turn on the water. When the hands are no longer sensed by the proximity sensor the water is turned off.
There are many different types of proximity sensors. One type has a transmitter which transmits electromagnetic radiation of a predetermined wavelength range positioned adjacent to a receiver which is adapted to receive electromagnetic radiation in the predetermined wavelength range and generate a signal indicative of the amount of such electromagnetic radiation that is received. Infrared (IR) radiation transmitters and receivers are often used. In operation, an IR transmitter transmits IR radiation which strikes a nearby object and is reflected by the object back towards the transmitter and receiver. IR radiation reflected by the object onto the receiver is sensed by the receiver which generates a signal indicative of the amount of IR radiation striking it. A signal of sufficient magnitude indicates the likely presence of a nearby object.